Electrogasdynamic power generation

ABSTRACT

Improved constructions for electrogasdynamic power generators wherein localized disruptive disturbance of the streamlined flow path of vapor containing gas therethrough is effected by selectively located sharp edged surface discontinuities in the flow defining channels thereof.

FIPSSUZ EJ HBBWH Dulles raw! owan Mar. 21, 11972 [54] ELECTROGASDYNAMIC POWER [56] References Cited GENERATION UNITED STATES PATENTS [72] Inventor: Philip L. Cowan, 112 Galloping Hill Road, 2 302 185 H1942 Campbell 317/3 UX Baskmg 07920 2,565,454 8/1951 MacKenzie 310 10 0x [22] Filed: Dec. 19, 1969 3,225,225 12/1965 Wattendorf.... ..310/6 3,417,267 12/1968 Marks ..310/6 [21] Appl. No.: 886,487

Related U.S. Application Data jgz igi gggggij [63] Continuation-impart of Ser. No. 788,149, Dec. 31,

1968, abandoned. [57] ABSTRACT Improved constructions for electrogasdynamic power genera- [52] U.S. Cl ..310/10 tors wherein localized disruptive disturbance of the stream [51] Ill. Cl. lined fl p of vapor containing g therethrough is [58] Fleld of Search ..3 10/5, 6, 10, l 1; 317/3, 4; fected by Selectively located Sharp edged Surface discontinui ties in the flow defining channels thereof.

25 Claims, 5 Drawing Figures PAIENTEDMAR21 I972 SHEET 1 OF 4 INVENTOR. PHILIP L. COWAN ATTORNEY PATENTEDNARZ] I972 sum 2 0F 4 AIR our AIR IN INVENTOR. PHILIP L.

COWAN PATENTEDMAR21 1972- SHEEI 3 or 4 llllllllllllllllllllllll! INVENTOR. PHILIP L COWAN ATTORNFY PATENTEBMARZI m2 SHEET [1F 4 mum-I i w d II II N Ii II I IIIIII This invention relatesto the generation of electrical power and particularly to improved constructions for electrogasdynamic power generators.

The electrogasdynamic generation ofelectrical power,

wherein the kinetic energy of moving gas stream is converted into electrical energy characterized by the permitted obtaining of extremely high potentials, has been long recognized as an interesting scientific phenomemon. The commercial development and practical utilization thereof however has been extremely limited due, at least in part, to the difficulties of introducing the requisite seed material into the moving air stream in sufficient amounts to ensure operability and minimize difficulties in the exhaust thereof and to lack of operational reliability of the available generator units. Also, it has been generally considered important in the design of efficient vaporous seeded electrogasdynamic power generators to create relatively smooth contours over which the gas flows to provide a streamline passage and thereby minimize frictional pressure drops.

This invention may be briefly described as an improved electrogasdynamic power generation system including an improved construction for an electrogasdynamic power generator. In its more detailed aspects, the subject invention includes the selective introduction of surface discontinuities which cause a disruptive disturbance in the gas flow in the vicinity of the charging zone and abrupt expansion in the cross-sectional area of the gas flow passage following the charging zone which provides marked improvement in the generator performance particularly at low pressures.

The primary object of this invention is the provision of improved generator constructions for the electrogasdynamic generation of electrical power.

Another object of this invention is the provision of an improved construction for electrogasdynamic power generators that permits reductions in the size thereof with markedly increased power output therefrom.

Other objects and advantages of the subject invention will become apparent from the following portions of the specification and from the appended drawings which illustrate, in accord with the mandates of the patent statutes, the principles of the invention as embodied in an electrostatic type spray painting system.

REFERRING TO THE DRAWINGS FIG. 1 is a schematic representation of an air atomized electrostatic spray painting system.

FIG. 2 is a vertical section of a vapor introducing seed pot assembly.

FIG. 3 is a schematic representation, partly in section, illustrative of the inclusion of an improved electrogasdynamic voltage generator constructed in accord with the principles of this invention in an air atomized type of paint spray gun.

FIG. 4 is a vertical section of an alternative construction for an electrogasdynamic power generator cartridge incorporating the principles of this invention; and

FIG. 5 is a sectional view of additional constructional modifications for the transition section for an electrogasdynamic power generator cartridge incorporating the principles of this invention.

Referring to the drawings and initially to FIG. 1, there is generally illustrated the elements of hand-manipulable type of air atomized electrostatic paint spraying system incorporating as a component generator constructions of this invention. As shown, such system conventionally includes a compressed air supply hose connectable to a remote source of compressed air (not shown) suitably of a pressure of about p.s.i.g. or greater, that serves to conjointly supply fluid paint delivery pressure through a T-type fitting 12 and associated regulator and gauge assembly 14 to a paint supply pot l6 and to supply the necessary air utilizable for atomization and electric power generation through line 18 to a vapor seed pot assembly 26. The line 18 is desirably provided with an independent regulator and gauge assembly, generally designated 20, to provide discrete and independent operational control over the pressure and the flow rate of the air conveyed to the air atomized paint spraying device, generally designated 28 and suitably constituting a hand-manipulable .air atomized spray gun. The paint supply pot 16, which is also of conventional character, is

. desirably supported on an insulating stand 22 and fluid paint is conveyed therefrom to the insulating barrel portion 34 of the spray gun 28 through an insulated paint supply hose 24 so as to ensure, when conducting paintsare being utilized, against possible shorting of the voltage carrying spray gun components to ground through the above described components of the paint supply system.

As noted above, air is introduced into the vapor seed pot assembly 26 wherein small quantities of seed material, here suitably an inexpensive and conventionally employed paint solvent of a character compatible with the fluid paint being employed, is selectively introduced thereinto in the form of vapor. Upon exiting from the vapor seed pot assembly, the now seeded air is transported via-the single supply hose 30 to the air atomized spray device 28 for utilization therein for the conjoint purposes of effecting atomization of liquid coating material, shaping of the atomized material if desired for the generation of electric power for effecting electrostatic deposition of the atomized liquid as described in detail in my copending application Ser. No. 788,148 filed Dec. 31, 1968. For the purposes of this application, the vapor containing air or other gas conveyed via the common supply line 30 from the locus of seed material introduction to the electrogasdynamic power generator will be hereinafter termed as the seeded air" irrespective of the particular utilization or disposition thereof that is made or effected after its introduction into the spray device and passage through the electrogasdynamic power generator contained therein.

The compressed air supply hose 10, the paint supply hose 24 and the atomizing air supply hose 18 are suitably constructed of electrically insulating material, as is the seeded atomizing air supply hose 30, with the latter desirably containing a metallic conductor element, suitably in the form of a sheath or strand, which serves to ground the conducting handle portion 32 of the air atomized spray device 28 through the grounded vapor seed pot assembly 26.

The workpiece or object 42 to be coated is suspended, in a manner conventional in electrostatic spray painting systems, from a grounded support assembly generally designated 44 and which may comprise a conveyor device or the like to sequentially present successive articles to be coated in predetermined spaced relation with the path of the emitted spray 46 from the spray device 28.

As schematically illustrated in FIG. 1, the spray gun 28 may suitably comprise a hand-manipulable unit having a generally cylindrical barrel portion 34 with a conducting pistol grip type handle portion 32 mounted at one end thereof and an atomizing nozzle charging electrode assembly, generally designated 36, disposed at the other end thereof. The spray gun 28 may broadly include other conventional fluid paint delivery systems and atomizing nozzle assemblies in conjunction with an improved self-contained cartridge type electrogasdynamic power generating device of this invention disposed in the flow path of at least a portion of the seeded atomizing air and having its excitation voltage supplied from a remote source 38 thereof via a lead 40, suitably comprising an unshielded conductor wire fastened directly to or contained within the seeded atomizing air supply line 30.

FIG. 2 is a sectional view of a suitable construction for the vapor seed assembly pot 26 that is included in the air supply conduits for the electrogasdynamic power generator for introduction of the seed vapor material necessary for operation of the electrogasdynamic generator. Such illustrated construction has proved to be particularly effective for ensuring the introdu ction of the requisite seed material into the air supply in the form of vapor and without detrimental pick up of liquid in droplet form and undesired excessive cooling of the moving air stream by the processes of evaporation.

As illustrated, the subject construction includes a cylindrically shaped lower liquid reservoir portion 52 and a cap member 54 threadedly engageable therewith as at 56. The cap member 54 includes a cylindrical and open ended dependent skirt portion 58 which extends downwardly into the liquid reservoir 52 and an upper portion 60 defining a transfer chamber 62. Superimposed on the upper portion 60 is a connector assembly 64 having a central bore 66 communicating with the chamber 62 and having air admission and air exit conduits 63 and 70 respectively connected to said chamber. Axially disposed within the bore 66 is a shaft 72 having a transversely disposed deflector plate 74 terminally mounted thereon. The deflection plate 74 should be slightly smaller than the interior dimension of the upper section 54 and disposedadjacent to the surface of the seed liquid 76 in the reservoir. As indicated by the arrows 78, the deflection plate 74 serves to minimize, if not prevent, direct contact of the air passing through the units with the surface of the liquid in the reservoir.

Disposed in interfacial engagement with the interior surface of the cap member 54 over substantially its entire length is a covering or layer of wicking material 80 which extends down into the contained liquid and serves as an extended capillary surface for introducing an extended surface thin film of liquid seed material over the walls of the chamber 62.

In operation of the described unit, the cap member 54 is threadedly engaged with the seed liquid containing lower reservoir portion 52. After such assembly the two components conjointly form a sealed unit desirably having liquid level disposed slightly below the undersurface of the deflection plate 74. Air or other gas is then introduced into the interior of the pot through the conduit 63 and, in passing through the bore 66 is discharged generally downward around the shaft 72 as shown by the arrows 78. The interposition of the deflecting plate 74 serves to prevent the introduced air from impinging directly upon the surface of the seed liquid and directs the same outwardly at reduced velocities adjacent the wicking material 80. As the air moves upwardly along the periphery of the chamber 62 in interfacial relation with the exposed surface of the wick material, it selectively entrains the liquid seed material in the form of vapor from the latter. It should be noted that in the evaporation region, i.e., the region located within the chamber 62, the wick material 80 is disposed in intimate interfacial contact with the metallic walls of the cap member 54 to provide a relatively good heat transfer assembly with respect to the outside air and the evaporating liquid surface. After thin upward passage within the chamber 62, the now vapor laden gases exhaust from the seed pot through the exit conduit 70 and the seeded effluent is then ready for transmittal to the electrogasdynamic power generator. In the particular embodiment that is shown in FIG. 1 by way of example the air hose 30 leading from the seed pot 26 to the spray device contains a grounded sheath and the seed pot is affirmatively grounded to prevent any possibility of charge build up thereon or possible sparking during operation or during the necessary filling thereof when required.

By way of specific example, FIG. 3 illustrates the inclusion of an electrogasdynamic power generator of the improved construction of this invention in an electrostatic air atomized type of spray gun. As previously noted the subject gun includes, in its broad aspects, an insulating barrel portion 34 having a pistol grip type of conducting handle portion 32 mounted at one end thereof and an atomizing and charging assembly, generally designated 36, disposed at the other end thereof. Included therewithin and located in the upper portion of the barrel 34 is the electrogasdynamic power generator, generally designated 50, operably responsive to the flow of seeded atomizing air therethrough together with provision for introducing the necessary excitation voltages thereto via the lead 66 through the handle member 32.

As shown in section, the upper portion of the insulating barrel 34 contains a relatively large elongate bore 156 which is adapted to removably receive an electrogasdynamic power generator assembly, generally designated 50, constructed in accord with the principles of this invention and in which the electric power necessary to charge the atomized paint spray particles and to create the electrostatic depositing field is derived from the direct conversion of the kinetic energy of the moving stream of seeded atomizing air. In the illustrated unit, the seeded atomizing air under pressure is introduced, in response to actuation of the trigger 96, through the bore 112 into an annularly shaped entry or inlet conduit section 114 of the electrogasdynamic power generator which entry section is of relatively large cross-sectional area so as to produce a relatively low subsonic flow velocity and minimal pressure drop to maintain a pressure of at least 15 pounds per square inch gauge therewithin. Disposed within the entry section 1M is the extending portion of an insulated mounting sleeve assembly 190 which serves to coaxially position an elongate ionizer needle electrode 124 relative to a surrounding converging transition section 192 and an annular attractor electrode 194. Such sleeve assembly 190 also serves to provide a receiving support for the end of the excitation supply voltage lead 66 which, in the illustrated embodiment, is connected to v the said ionizer needle electrode 124. The ionizer electrode needle 124 extends axially downstream within the transition section 192 to the attractor electrode ring 194 which operatively effects a marked decrease in the cross-sectional flow area for the moving seeded atomizing air stream and serves to increase the speed thereof as it approaches the attractor ring to a velocity in the vicinity of the sonic velocity. After passage through the attractor ring electrode 194, the atomizing air stream passes through an elongate channel 158 of relatively small, but preferably slightly increasing in the direction of flow, cross-sectional area suitably sized so that, within which and under the pressure conditions extant, the flow velocity of the seeded atomizing air will be maintained markedly higher than that extant in the entry section 114 and which, for good performance should preferably be maintained in the vicinity of the sonic velocity. After exiting from the channel 158 the atomizing air stream impinges against an axially disposed collector needle electrode 198 mounted in a plug 196 and expands into the bore 156 and flows therewithin at reduced velocities toward the exit conduit therefrom. As shown the collector needle electrode 198 is directly connected as by a lead 200 to the charging electrode element for the electrostatic deposition system.

In operation of the described unit, application of excitation voltage, suitably in the order of 5,000 volts, to the ionizer needle electrode 124 will initiate a corona discharge condition and cause a corona current to flow in the gap between the point of the ionizer needle electrode 124 and the adjacent attractor ring electrode 194 forming a corona discharge zone. Concurrently therewith, the seeded atomizing air moving through the gun will travel from the bore 112 and entry section 114 into the converging inlet section ahead of the attractor electrode ring 194 and through the corona discharge area or zone as it approaches the vicinity of the sonic velocity in its passage through the attractor electrode ring 194. Under corona discharge conditions as described above, the passage of the seeded atomizing air therepast at near sonic speeds will result in condensation of at least a portion of the seed vapor therein to form an aerosol in the form of extremely small parti cles or droplets around the unipolar ions present in the corona discharge zone. The ions about which the seed material condenses are thereby degraded in mobility, become fixed or nearly so in the stream of moving atomizing air and are swept out of the corona discharge area, past the attractor ring electrode 194 and down the elongate insulating channel 158 at high velocity, as for example at speeds in the vicinity of the sonic velocity. The charges in the moving gas stream will then be collected at the collector electrode 198 and will raise the potential thereof to extremely high values, with such potential being applied by the conductor 200 to the charging electrode 36. The application of such high potential to the charging electrode 36 will create a corona discharge condition adjacent the terminus thereof and an area rich in unipolar ions closely adjacent to the locus of atomization, which ions will, if the electrode is suitably shaped, attach themselves to the atomized paint particles and selectively charge the same. Under such conditions the charging electrode will also serve as one terminus of an electrostatic depositing field with the other terminus thereof being constituted by the grounded object to be coated.

In electrogasdynamic power generators of the general type described, the initiation of the requisite corona discharge at the entrance to the channel 158 requires the application of only relatively low excitation voltages, as for example in the order of 5,000 volts, in order to effect the generation of very high voltage at the collector electrode 198. The load current and voltage can be much higher than that of the excitation supply, since the electrical power generated is derived from the kinetic energy of the moving gas stream which does the necessary work in driving the ions along the channel 158 from the attractor ring electrode 194 to the collector electrode 198 against the opposing electrical field. It should be noted that although convenience has here dictated application of the excitation voltage to the ionizer needle 124 and having the attractor ring electrode 194 grounded, such can be readily reversed and operations effected with a grounded needle electrode and a charged attractor electrode with the necessary constructional modification relative to insulation and the like. In the electrogasdynamic power generator, the maximum output voltage thereof is essentially determined by the voltage at which electric breakdown will occur between the collector electrode and ground, and in the unit shown in FIG. 3 such breakdown will most likely occur between the collector and attractor electrodes along the walls of the channel 158. As such, the length of the insulating channel 158 employed provides a convenient control of the magnitude of the maximum voltage obtainable from the system and different generator cartridges can be made available in accord with the exigencies of the desired use thereof.

FIG. 4 illustrates in enlarged scale the improved construc tion for electrogasdynamic power generators in accord with this invention which provides, in a diminutive size unit adapted for cartridge type utilization and employing velocities in the vicinity of the sonic velocity in the attractor electrode and the generator channel, high performance characteristics over a wide range of operating pressures and mass flow rates. As previously described in conjunction with FIG. 3, the subject generator includes an ionizer needle I24 coaxially disposed, relative to the axis of the channel 158 formed by the insulating sleeve 212, by a mounting member 190 and sized to extend through a converging inlet or transition section to the proximity of the attractor ring electrode 194 as defined by the conically bored insulating member 192. Preferably all such units are preassembled and permanently secured in desired position so as to facilitate unit replacement of the generator assembly when desired, thus making the spray gun readily field serviceable in the event of failure or deterioration. In this illustrated embodiment, the excitation voltage is connected to the attractor ring electrode 194 as an alternative to the previously described construction and the needle electrode 124 is operated at ground potential. With proper design almost all of the current flowing from the ionizer needle 124 can be caused to move with the atomizing air downstream to the collector needle electrode 196 which operates to effectively minimize the excitation power required since under such conditions the current flowing in the excitation circuit approaches zero in value. As noted earlier, the subject electrogasdynamic power generator is proportioned so that the flow of atomizing air through the attractor ring electrode and in the elongate channel 158 is near sonic in character which provides high performance at pressure drops of a magnitude that are essentially compatible with common paint chop compressor delivery characteristics. In addition thereto, and in accord with the preamblesof this invention the portions of the generator disposed immediatelyadjacent to the attractor ring electrode.

194 are selectively shaped to provide one or more relatively sharp edged surface discontinuities in the walls defining the air flow path therepast and to thereby provide at at least one exposed surface fusing the incoming gas flow.One simple means for introducing such a surface discontinuity as shown in FIG. 3, is to make the inside diameter of the downstream end of the converging inlet section 192 somewhat larger than the inside diameter of the attractor ring electrode 194 to effectively provide an exposed surface in the nature of an annular shoulder extending at right angles to and facing the longitudinal axis of the flow path. An alternate means of obtaining, such a desired configuration, however, is to incorporate, as shown in FIG. 4 an annular recess 220 intermediate the attractor ring electrode 194 and the downstream end of the transition member 192. Such a recess provides a short section of abruptly expanded cross section gas flow area. An alternate or supplemental and, in fact, preferred construction includes the incorporation of a second annular recess 216 adjacently downstream of the attractor ring electrode 194 and suitably located intermediate the attractor ring electrode 194 and the entrance portion of the channel 158 as shown in both FIGS. 3 and 4, which is of a transverse diameter significantly greater than the air passage defined by the ring and channel.

Experiments to date have indicated that while the longitudinal and transverse dimension of the recess 220 disposed upstream of an attractor electrode is not attended with any great degree of criticality, the downstream recess disposed intermediate the attractor electrode and the entrance portion of the channel preferably has a longitudinal extent that is less than one attractor ring diameter and transverse diameter that at least exceeds that of the entrance portion of the channel. Another desirable construction for providing an abruptly expanded cross section gas flow area adjacently downstream of the attractor ring electrode and which may be employed either alone or in conjunction with a downstream recess is to make the internal diameter of the entrance portion of the channel 158 larger than the diameter of the attractor ring electrode 194. Test results to date indicate that an enlargement in area of at least about 5 percent and extending up to about 30 percent for this latter embodiment provides enhanced performance. Additionally the channel 158 desirably should diverge slightly in cross-sectional extent in the direction of air flow to ensure maintenance of near sonic velocities in the vicinity of the attractor electrode 194.

While improved performance apparently results from the use of any of the above described constructional features, most, if not all of the above means are desirably incorporated in the generator as disclosed in FIG. 4. While the reasons for the improved performance obtained by the incorporation of such type of structure are not clearly or fully understood at the present time it is believed that the sharp edged discontinuities into the defining walls of the system and providing an exposed surface facing the direction of incoming gas flow function to disruptively disturb the streamlined flow of gas and introduce a high degree of turbulence into the flow through the attractor ring electrode 194 and the channel 158 and which also may serve to minimize build up of a relatively slow moving gas layer along the wall portions within the attractor ring electrode 194 and within the channel 158.

In addition, in extended tests, a thin film of contaminant believed to be the oil residue from the compressor appears to build up along the channel wall. Such film build up apparently functions to choke the flow through the elongate channel with a concommitant drop in performance. With the oversized channel entrance as described above the effective operating life at high performance is markedly extended.

In general a channel entrance no less than 2 percent nor greater than 15 percent larger in diameter or transverse dimension than the attractor electrode aperture is preferred. Likewise at the entrance to the attractor electrode a positive step of at least 2 percent between the transition end and the attractor aperture appears to be required. Also the recesses 220 and 226 should be of a length that is less than one attractor diameter.

FIG. illustrates another alternative means whereby the desired surface discontinuities may be introduced into the defining walls of the generator adjacent by upstream the attractor ringelectrode 194. In this embodiment, the converging inlet or transition section 192 is shaped to provide a series of steps or shoulders defining radial surfaces facing the incoming flow of seeded air each terminating in a sharp edged surface discontinuity therein.

By way of specific example, markedly improved performance has been obtained with a spray gun incorporating an electrogasdynamic power generator of the type illustrated in FIGS. 3 and 4 having the following dimensions and operating with an air fiow velocity in the vicinity of the sonic velocity in the channel 158 under the following operating parameters:

Atomizing air delivery pressures of from 20l00 p.s.i.g. Attractor ring electrode I94 0.] 16" ID by ().I I7" long Converging or transition section Recess 220 Recess 2I6 Channel I58 Such a generator configuration provides high voltage performance over a wide pressure range and readily delivers currents of about one microampereper pound per square inch gauge of supply pressure.

In general the materials of construction do not appear to be of prime importance although some of the insulating portion thereof, as for example, the channel 158 and mounting member 190 (when the ionizer needle is subjected to the excitation voltage) should be formed of insulating material of high dielectric strength.

While I have shown and described certain presently preferred embodiments incorporating the principles of my invention, it should be understood that the same is capable of modification. Changes, therefore, in both constructions may be made without departure from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

1, In an electrogasdynamic power generator attractor electrode means shaped to define a passage for the flow of a condensable vapor containing gas therethrough at a speed in the vicinity of the sonic velocity,

a conduit section disposed on the upstream side of said attractor electrode means to direct the flow of said condensable vapor containing gas thereto,

means defining at least one relatively sharp edged surface discontinuity adjacently upstream of said attractor electrode means to provide at least one surface directionally exposed to the flow of said incoming condensable vapor containing gas adapted to introduce a zone of disruptive disturbance into the streamlined flow of said vapor containing gas therepast,

and ionizing electrode means positioned within said conduit section to provide a discharge current flow path disposed at least in part within said zone of disruptively disturbed gas flow,

whereby an aerosol of low mobility particles is formed by condensation of said vapor in said discharge zone.

2. In an electrogasdynamic power generator inlet conduit means for conveying a low subsonic velocity flow of gas containing a condensable vapor at a pressure of at least pounds per square inch,

transition means disposed at the terminal end of said inlet conduit means for expanding said condensable vapor containing gas to a velocity in the vicinity of thespeed of sound,

means defining at least one relatively-sharp edged surface discontinuity in said transition means providing a surface directionally exposed to the flow of said incoming condensable vapor containing gas adapted to introduce a zone of localized disruptive disturbance to the streamlined flow of the expanding vapor containing gas therepast,

and ionizing electrode means positioned to provide a corona discharge zone disposed, at least in part, coincident with said zone of disruptively disturbed gas flow whereby an aerosol of low mobility particles is formed by condensation of said vapor in said discharge zone.

3. The generator construction as set forth in claim I including an elongate channel section disposed on the downstream side of said attractor electrode means for conveying said gas therefrom at speeds in the .vicinity of the speed of sound,

and means defining an abrupt enlargement of the cross-sectional area of the gas flow defining passage adjacently downstream of said attractor electrode means.

4. The generator construction as set forth in claim 3 wherein said elongate channel section is of increasing crosssectional area in the direction of gas flow therethrough along the major portions of its length.

5. The generator construction as set forth in claim 3 wherein said last mentioned means defines a recess of limited longitudinal extent disposed intermediate the attractor electrode means and the entrance portion of said elongate channel section.

6. The generator as set forth in claim 3 wherein said last mentioned means comprises the entrance portion of said elongate channel section sized to be between 5 and 30 percent larger in cross-sectional area than the exit portion of said attractor electrode means.

7. The generator construction as set forth in claim 3 wherein said last mentioned means defines a recess of limited longitudinal extent disposed intermediate the attractor electrode means and the entrance portion of said elongate channel section and wherein said entrance portion of said elongate channel section is sized to be between 5 and 30 percent larger in cross-sectional area than the exit portion of said attractor electrode means.

8. In an electrogasdynamic power generator,

attractor electrode means shaped to define a passage for the fiow of a condensable vapor containing gas therethrough at a speed in the vicinity of the sonic velocity, an elongated channel section disposed on the downstream side of said attractor electrode means for conveying said gas therefrom at speeds in the vicinity of sonic velocity,

and recess means of limited longitudinal extent disposed intermediate said attractor electrode means and the entrance portion of said elongated channel section defining an abrupt enlargement of the cross sectional area of the gas flow defining passage adjacently downstream of said attractor electrode means.

9. The generator construction as set forth in claim 8 wherein the entrance portion of said elongate channel section is sized to be between 5 and 30 percent larger in cross-sectional area than the exit portion of said attractor electrode means.

10. The generator construction as set forth in claim 9 wherein said elongate channel section is of increasing crosssectional area in the direction of gas flow therethrough.

11. The generator construction as set forth in claim 2 wherein said means defining said sharp edged surface discontinuity comprises an annular recess disposed adjacent the downstream of said transition means.

12. The generator construction as set forth in claim 1 wherein said surface discontinuity defining means comprises an exposed surface of said attractor electrode means disposed substantially perpendicular to the direction of gas flow.

13. In an electrogasdynamic power generator attractor electrode means shaped to define a passage for the flow of a condensable vapor containing gas therethrough at a speed in the vicinity of the sonic velocity,

a conduit section disposed on the upstream side of said at- .tractor electrode means to direct the flow of said condensable vapor containing gas thereto,

recess means defining an abrupt enlargement of the crosssectional area of said conduit section disposed adjacently upstream of said attractor electrode means and in the flow path of said incoming condensable vapor containing gas for disruptively disturbing the streamlined flow of said vapor containing gas,

and ionizing electrode means positioned within said conduit section to provide a discharge current flow path disposed at least in part within said disruptively disturbed gas flow,

whereby an aerosol of low mobility particles is formed by condensation of said vapor in said discharge zone.

14. In an electrogasdynamic power generator, attractor electrode means shaped to define a passage for the flow of gas containing a condensable vapor therethrough,

a transition section disposed on upstream side of said attractor electrode to accelerate the flow of air therethrough prior to its introduction into said attractor electrode,

an ionizing electrode disposed within said transition section,

an elongate channel section of gradually increasing crosssectional area in the direction of flow disposed on the downstream side of said attractor electrode,

a collector electrode disposed adjacent the terminal end of said channel section,

and means defining at least one recess adjacent to said attractor electrode having a cross-sectional area greater than the air passage through said attractor electrode.

15. The combination as set forth in claim 14 wherein said recess is disposed intermediate said transition section and said attractor electrode.

16. The combination as set forth in claim 14 wherein said recess is disposed intermediate said attractor electrode and the entry portion of said elongate channel section.

17. The combination as set forth in claim 16 wherein the entry portion of the elongate channel section is of greater cross-sectional area than the air flow passage at the exit of said attractor electrode.

18. In the electrogasdynamic generation of electrical power wherein the kinetic energy of a moving gas stream is converted into electrical energy, the steps of maintaining a corona discharge zone by a flow of discharge current from an ionizing electrode to an attractor electrode expanding a condensable vapor containing gas into the corona discharge zone at speeds in the vicinity of the sonic velocity to form a charged aerosol of low mobility, therewithin,

removing said aerosol from said corona discharge zone at speeds in the vicinity of the sonic velocity, and

disruptively disturbing the streamlined flow of said gas in the vicinity of said corona discharge zone by impacting a portion thereof against at least one relatively sharp edged discontinuity projecting outwardly into the flow of the moving gas stream adjacently upstream of the attractor electrode.

19. In the electrogasdynamic generation of electrical power wherein the kinetic energy of a moving gas stream is converted into electrical energy, the steps of maintaining a corona discharge zone by a flow of discharge current from an ionizing electrode to an attractor electrode,

expanding a condensable vapor containing gas into said corona discharge zone at speeds in the vicinity of the sonic velocity to form a charged aerosol of low mobility therewithin,

removing said charged aerosol from said corona discharge zone at speeds in the vicinity of the sonic velocity, and

disruptively disturbing the streamlined flow of said gas in the vicinity of said corona discharge zone by passing the moving gas stream past a recess defining an abrupt enlargement of the cross-sectional area of the gas flow defining passage.

20. The method steps as set forth in claim 19 wherein said disruptive disturbance of the streamlined flow of said gas is effected adjacently upstream of said attractor electrode.

21. In an electrogasdynamic power generator,

attractor means shaped to define a passage for the flow of a condensable vapor containing gas therethrough at a speed in the vicinity of sonic velocity,

an elongated channel section disposed on the downstream side of said attractor electrode means and continuous therewith for conveying said gas therefrom at speeds in the vicinity of sonic velocity,

the entrance portion of said elongated channel section being enlarged with respect to the portion of said elongated channel section immediately downstream thereof and the inlet of said entrance portion being selectively sized to be between 5 and 30 percent larger in cross-sectional area than the exit portion of said attractor electrode means.

22. The method according to claim 19 wherein said disturbance of the streamlined flow of said gas is effected adjacently downstream of said attractor electrode.

23. An electrogasdynamic power generator according to claim 1 wherein said means for defining at least one relatively sharp edged surface discontinuity comprises annular shoulder means extending substantially at right angles to and facing the longitudinal axis of the flow path of the condensable vapor containing gas.

24. An electrogasdynamic power generator according to claim 23 further comprising a plurality of said annular shoulder means.

25. An electrogasdynamic power generator according to claim 1 wherein said means for defining at least one relatively sharp edged surface discontinuity comprises annular recess means adjacently upstream of said attractor electrode means. 

1. In an electrogasdynamic power generator attractor electrode means shaped to define a passage for the flow of a condensable vapor containing gas therethrough at a speed in the vicinity of the sonic velocity, a conduit section disposed on the upstream side of said attractor electrode means to direct the flow of said condensable vapor containing gas thereto, means defining at least one relatively sharp edged surface discontinuity adjacently upstream of said attractor electrode means to provide at least one surface directionally exposed to the flow of said incoming condensable vapor containing gas adapted to introduce a zone of disruptive disturbance into the streamlined flow of said vapor containing gas therepast, and ionizing electrode means positioned within said conduit section to provide a discharge current flow path disposed at least in part within said zone of disruptively disturbed gas flow, whereby an aerosol of low mobility particles is formed by condensation of said vapor in said discharge zone.
 2. In an electrogasdynamic power generator inlet conduit means for conveying a low subsonic velocity flow of gas containing a condensable vapor at a pressure of at least 15 pounds per square inch, transition means disposed at the terminal end of said inlet conduit means for expanding said condensable vapor containing gas to a velocity in the vicinity of the speed of sound, means defining at least one relatively sharp edged surface discontinuity in said transition means providing a surface directionally exposed to the flow of said incoming condensable vapor containing gas adapted to introduce a zone of localized disruptive disturbance to the streamlined flow of the expanding vapor containing gas therepast, and ionizing electrode means positioned to provide a corona discharge zone disposed, at least in part, coincident with said zone of disruptively disturbed gas flow whereby an aerosol of low mobility particles is formed by condensation of said vapor in said discharge zone.
 3. The generator construction as set forth in claim 1 including an elongate channel section disposed on the downstream side of said attractor electrode means for conveying said gas therefrom at speeds in the vicinity of the speed of sound, and means defining an abrupt enlargement of the cross-sectional area of the gas flow defining passage adjacently downstream of said attractor electrode means.
 4. The generator construction as set forth in claim 3 wherein said elongate channel section is of increasing cross-sectional area in the direction of gas flow therethrough along the major portions of its length.
 5. The generator construction as set forth in claim 3 wherein said last mentioned means defines a recess of limited longitudinal extent disposed intermediate the attractor Electrode means and the entrance portion of said elongate channel section.
 6. The generator as set forth in claim 3 wherein said last mentioned means comprises the entrance portion of said elongate channel section sized to be between 5 and 30 percent larger in cross-sectional area than the exit portion of said attractor electrode means.
 7. The generator construction as set forth in claim 3 wherein said last mentioned means defines a recess of limited longitudinal extent disposed intermediate the attractor electrode means and the entrance portion of said elongate channel section and wherein said entrance portion of said elongate channel section is sized to be between 5 and 30 percent larger in cross-sectional area than the exit portion of said attractor electrode means.
 8. In an electrogasdynamic power generator, attractor electrode means shaped to define a passage for the flow of a condensable vapor containing gas therethrough at a speed in the vicinity of the sonic velocity, an elongated channel section disposed on the downstream side of said attractor electrode means for conveying said gas therefrom at speeds in the vicinity of sonic velocity, and recess means of limited longitudinal extent disposed intermediate said attractor electrode means and the entrance portion of said elongated channel section defining an abrupt enlargement of the cross sectional area of the gas flow defining passage adjacently downstream of said attractor electrode means.
 9. The generator construction as set forth in claim 8 wherein the entrance portion of said elongate channel section is sized to be between 5 and 30 percent larger in cross-sectional area than the exit portion of said attractor electrode means.
 10. The generator construction as set forth in claim 9 wherein said elongate channel section is of increasing cross-sectional area in the direction of gas flow therethrough.
 11. The generator construction as set forth in claim 2 wherein said means defining said sharp edged surface discontinuity comprises an annular recess disposed adjacent the downstream of said transition means.
 12. The generator construction as set forth in claim 1 wherein said surface discontinuity defining means comprises an exposed surface of said attractor electrode means disposed substantially perpendicular to the direction of gas flow.
 13. In an electrogasdynamic power generator attractor electrode means shaped to define a passage for the flow of a condensable vapor containing gas therethrough at a speed in the vicinity of the sonic velocity, a conduit section disposed on the upstream side of said attractor electrode means to direct the flow of said condensable vapor containing gas thereto, recess means defining an abrupt enlargement of the cross-sectional area of said conduit section disposed adjacently upstream of said attractor electrode means and in the flow path of said incoming condensable vapor containing gas for disruptively disturbing the streamlined flow of said vapor containing gas, and ionizing electrode means positioned within said conduit section to provide a discharge current flow path disposed at least in part within said disruptively disturbed gas flow, whereby an aerosol of low mobility particles is formed by condensation of said vapor in said discharge zone.
 14. In an electrogasdynamic power generator, attractor electrode means shaped to define a passage for the flow of gas containing a condensable vapor therethrough, a transition section disposed on upstream side of said attractor electrode to accelerate the flow of air therethrough prior to its introduction into said attractor electrode, an ionizing electrode disposed within said transition section, an elongate channel section of gradually increasing cross-sectional area in the direction of flow disposed on the downstream side of said attractor electrode, a collector electrode disposed adjacent the terminal end of said channel section, and means defining at least one recess adjacent to said attractor electrode having a cross-sectional area greater than the air passage through said attractor electrode.
 15. The combination as set forth in claim 14 wherein said recess is disposed intermediate said transition section and said attractor electrode.
 16. The combination as set forth in claim 14 wherein said recess is disposed intermediate said attractor electrode and the entry portion of said elongate channel section.
 17. The combination as set forth in claim 16 wherein the entry portion of the elongate channel section is of greater cross-sectional area than the air flow passage at the exit of said attractor electrode.
 18. In the electrogasdynamic generation of electrical power wherein the kinetic energy of a moving gas stream is converted into electrical energy, the steps of maintaining a corona discharge zone by a flow of discharge current from an ionizing electrode to an attractor electrode expanding a condensable vapor containing gas into the corona discharge zone at speeds in the vicinity of the sonic velocity to form a charged aerosol of low mobility, therewithin, removing said aerosol from said corona discharge zone at speeds in the vicinity of the sonic velocity, and disruptively disturbing the streamlined flow of said gas in the vicinity of said corona discharge zone by impacting a portion thereof against at least one relatively sharp edged discontinuity projecting outwardly into the flow of the moving gas stream adjacently upstream of the attractor electrode.
 19. In the electrogasdynamic generation of electrical power wherein the kinetic energy of a moving gas stream is converted into electrical energy, the steps of maintaining a corona discharge zone by a flow of discharge current from an ionizing electrode to an attractor electrode, expanding a condensable vapor containing gas into said corona discharge zone at speeds in the vicinity of the sonic velocity to form a charged aerosol of low mobility therewithin, removing said charged aerosol from said corona discharge zone at speeds in the vicinity of the sonic velocity, and disruptively disturbing the streamlined flow of said gas in the vicinity of said corona discharge zone by passing the moving gas stream past a recess defining an abrupt enlargement of the cross-sectional area of the gas flow defining passage.
 20. The method steps as set forth in claim 19 wherein said disruptive disturbance of the streamlined flow of said gas is effected adjacently upstream of said attractor electrode.
 21. In an electrogasdynamic power generator, attractor means shaped to define a passage for the flow of a condensable vapor containing gas therethrough at a speed in the vicinity of sonic velocity, an elongated channel section disposed on the downstream side of said attractor electrode means and continuous therewith for conveying said gas therefrom at speeds in the vicinity of sonic velocity, the entrance portion of said elongated channel section being enlarged with respect to the portion of said elongated channel section immediately downstream thereof and the inlet of said entrance portion being selectively sized to be between 5 and 30 percent larger in cross-sectional area than the exit portion of said attractor electrode means.
 22. The method according to claim 19 wherein said disturbance of the streamlined flow of said gas is effected adjacently downstream of said attractor electrode.
 23. An electrogasdynamic power generator according to claim 1 wherein said means for defining at least one relatively sharp edged surface discontinuity comprises annular shoulder means extending substantially at right angles to and facing the longitudinal axis of the flow path of the condensable vapor containing gas.
 24. An electrogasdynamic power generator according to claim 23 further comprising a plurality of said annular shoulder means.
 25. An eleCtrogasdynamic power generator according to claim 1 wherein said means for defining at least one relatively sharp edged surface discontinuity comprises annular recess means adjacently upstream of said attractor electrode means. 